The norris peters co



(No Model.)

0. 0 HARRIS. MAGHINB FOR THE MANUPAGTURH'OP SCREW CUTTING DIES.

Patented June 27, 1893..

UNITED STATES PATENT OFFICE.

CLINTON O. HARRIS, OF OHIOOPEE FALLS, MASSACHUSETTS, ASSIGNOR OF ONE-HALF TO LEONARD W. BEMIS, OF SAME PLACE.

MACHINE FOR THE MANUFACTURE OF SCREW-CUTTING DIES.

SPECIFICATION forming part of Letters Patent No. 500,494, dated June 27, 1893.

Application filed August 1,1892. Serial No. 441.796. (No model.)

To all whom it may concern; the invention I provide a suitably driven Be it known that I, CLINTON O. HARRIS, a spindle, at, having attached to one end thereof citizen of the United States, residing at Ohicoa mill-cutter, b, of conical form. Another pee Falls,in the county of Hampden and State shaft, d, is comprised in the improved ma- 5 of Massachusetts, have invented new and chine which has on its end toward the milluseful Improvements in the Manufacture of cutter a die-holding device, 2. This spindle Screw-Cutting Dies, of which the following is is mounted in the journals, 0, c, of a tail-stock,

a specification. f. The tail-stock is transversely movable on This invention relates to improvements in the supporting block, g, therefor having the I0 machines for the manufacture of screw cutdove-tail engagement therewith, seen at h,

ting dies, especially relating to the back outand the transverse movements may be imting or backing off of the initial teeth of parted and nicely gaged by the screw, f havthe die which is common and necessary for iug the handwheel, said screw being engaged clearance. with the ear-piece of the block, g, to freely ro- IS The invention consists in means for effecttate therein without axial movement, and having the back cutting, all substantially as will ing a screw engagement with the tail-stock. hereinafter fully appear and be set forth in the The shaft, d, mounted in the journal blocks claims. of the tail-stock is adapted for a longitudinal The following description will be rendered movement, the same being imparted by the 20 clear by the accompanying drawings, in lever, 11, which is pivoted on the fixed stud, j, which and has a pin and slot engagement with the Figure 1 is aperspective view of a machine collar, It, on the shaft. The shaft-has, at its for carrying out the invention, the operation portion which isfitted within one of the jourupon the die being shown. Fig. 2 is a view nal bearings, a series of longitudinal grooves,

25 of a holder for a square die block, the teeth 'm, equal in number and in a corresponding of the die being shown as backed off, the porelative arrangement to the series of segsition of the back cutting mill beingindicated mental cutter teeth,z, in the die to be worked relative to one series of the cutting teeth. upon. A hole is formed through the top of Fig. 3 is a sectional view taken on the line thejournalinto whichislooselyplacedasmall 30 33, Fig. 2. Fig. 4: is a face view and prostud, at, having a rounded lower end, above jected central section of a screw cutting die which is a spring, n held for a downward formed within a round die block with the inireaction by the screw plug, a The hand tial teeth back-cut. Fig. 5 is a perspective wheel, 0, constitutes a convenient means for View of the die-holding device shown onthe effecting the rotational movements of the 8 5 machine illustrated in Fig. 1. shaft.

The well known screw die comprises a suit- The holder device, 6, for the die, here shown, able body or block with a central opening consists of a cylindrical block formed or attherethrough having the segments of internal tac'hed on the shaft with a round or square screw threads which constitute the screw cutsocket, 6 therein into which the round or 4o ting or die teeth, they being arranged in sesquare die-body fits. Within the socket, a ries as shown, and the initial or outermost gage-stud, p, is preferably fixed to engage one one or two teeth of each series is backed off of the throat apertures, y, of the die to preor reduced from the forward cutting corner, as vent it from tnrningin the holder, one of such seen at o, for clearance and to permit the cutapertures being formed between every two se- 5 45 for to come to its action upon the shaft or rod ries, z, of the die teeth; a set-screw, q, holds being screw cut. Heretofore, so far as known the die firmly in place in the holder. Said to me, this back-cutting has been performed gage stud, however, is not required when the by hand filing, a slow and tedious process, die is of rectangular form, as in Fig. 2. and one by which the uniformity of the re- Now the operation of the machine and mo 5o duction at the rear of the teeth has not been method of performing the back-cutting conusually attained. Therefore in carrying out sists,after the tail-stock has been properlylaterally adjusted to be in the proper offside line from the axis of the mill, so that the latter will come to work at the right place on the initial orouter teeth of a series of the die teeth,in forcing the shaft, by the lever, i, forwardly carrying the die sufficiently far against the mill cutter as to give the desired depth of the back out. It will be understood that the parts are so adjusted and manipulated that the reduction by the mill cutter is in a curved course corresponding to the circular shape of the cutter which begins at the inwardly prominent edge of the initial cutting tooth and extends outwardly and rearwardly therefrom, the line, 1;, in Figs. 2 and 4 indicating the boundary, at the forward face of the die, of the back-cut. The depth of this back-cut may be as great as desired and determined by the degree of inclination which the sides of the cutter have to its axis. Having backed off the initial tooth or teeth of one of the series, the shaft is withdrawn endwise to bring the die free from the cutter, when, by the handwheel, 0, the shaft, 01, is rotated until the snap catch, it, springs into the next properly spaced groove, on, when the shaft is again endwise moved to force the edge of the forward tooth of the next series against the mill cutter. These operations are repeated as many times as there are series of teeth in the die-cutter and then the latter is removed from the holder. It isobvious that the result would be the same were the spindle, a, which carries the cutter, I), made to slide inits bearings to move said cutter to and from the die, and the spindle, d, be permitted to turn but not to slide, and the die, or die-holder and die be simply turned to bring the points of the die to be milled, in proper position, successively, for the cutter to act thereupon.

I claim- 1. The combination with the cone-shaped rotary mill-cutter and a spindle for operating the same, of the tail-stock having theshaft, d, mounted to slide endwise and having the longitudinal grooves, m, therein, and carryin g at its end toward the mill cutter, a holder for the die to be operated upon, said tail-stock being mounted for a movement transversely relative to the axis of the mill-cutter and having the pivoted lever, i, thereon, for forcing the shaft endwise, the stud, n, engaging in either of said grooves, and the screw, 9, for moving said shaft transversely of the axis of the cutter while the latter is operating upon the die, substantially as set forth.

2. The combination with the rotary mill cutter of a shaft mounted for a rotational movement with its end near the said cutter, and the one being adjustable laterally relative to the other, and the said shaft havinga die-holding device with a socket therein, for the reception of the die, and the gage-pin, p, and said shaft adapted for rotational movements for successively bringing different series of the die-teeth to the action of the mill cutter.

' 3. The combination with the spindle, a, having the mill cutter, b, of the shaft, cl, set in offset bearings from said spindle and having the longitudinal grooves, m, m, and carrying the die holding device which comprises a socketed part with the gage-pin, p, the snap catch applied at the bearingof the shaft and adapted to engage said grooves and means for moving the shaft endwise, substantially as described.

4. The combination with the spindle, 0., having the conical mill cutter, I), of the block, g, and the tail-stock having the transverse dove-tail engagement therewith, and provided with the bearings, c, c, offset from the axis of the mill cutter, the shaft, (1, having the collar, k, and the socketed holder 8, with the gage-pin, p, and the longitudinal grooves, m, m, the screw, f supported for rotation on the block, g, and screw engaging the tailstock, and the lever, i, pivotally mounted on the tail-stock and having an engagement with the said collar, It, all substantially as described.

ULINTON O. HARRIS. Witnesses:

H. A. CHAPIN, L. W. BEMIs. 

